This invention generally relates to intraluminal catheters, such as balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA).
PTCA is a widely used procedure for the treatment of coronary heart disease. In this procedure, a balloon dilatation catheter is advanced into the patient's coronary artery and the balloon on the catheter is inflated within the stenotic region of the patient's artery to open up the arterial passageway and thereby increase the blood flow there through. To facilitate the advancement of the dilatation catheter into the patient's coronary artery, a guiding catheter having a preshaped distal tip is first percutaneously introduced into the cardiovascular system of a patient by the Seldinger technique through the brachial or femoral arteries. The catheter is advanced until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery, and the distal tip of the guiding catheter is then maneuvered into the ostium. A balloon dilatation catheter may then be advanced through the guiding catheter into the patient's coronary artery until the balloon on the catheter is disposed within the stenotic region of the patient's artery. The balloon is inflated to open up the arterial passageway and increase the blood flow through the artery. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation but not over expand the artery wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter can be removed therefrom.
Commercially available balloon catheters for angioplasty and other intravascular procedures usually comprise an elongated shaft with an inflatable dilatation member on a distal portion of the shaft and an adapter on the proximal end of the shaft for the delivery of inflation fluid through an inner lumen extending through the catheter shaft to the interior of the inflatable dilatation member. Additionally, a guidewire lumen may be provided along at least a section of the elongated shaft. The elongated shaft typically comprises a relatively stiff proximal shaft section and a relatively flexible distal shaft section to facilitate catheter maneuverability and, therefore, the ability to effectively position the catheter at a desired location within a patient. Generally, angioplasty catheter proximal shaft sections are made highly crystalline or semicrystalline in order to increase the strength and stiffness of the shaft section.
Polymeric tubular catheter components are typically formed by extrusion, although they may be made by a variety of methods depending on the material used and the desired characteristics of the component. For example, a catheter shaft may be formed by free extrusion, wherein melted polymeric material passes through an extrusion die over a mandrel. Upon exiting the extruder, the tube is typically passed into a quench bath. The wall thickness of an extruded tube is a function of the annular gap between the die and the mandrel, and post extrusion processing such as draw-down of the polymeric material. Draw-down is the ratio of the die diameter to the final diameter of the extruded article, and is therefore a measure of the thinning of the extruded article as it exits the extruder. Where a multi-layered article is desired, the layers may be co-extruded, or a second layer extruded over an existing polymeric tube.
It would be a significant advance to provide a catheter having a polymeric shaft that is substantially transparent. The present invention satisfies these and other needs.